Technical Field
This disclosure relates to output of a graphics circuit, in particular, to a display circuit of switchable external display ports.
Related Art
With the applications of the multimedia, including the videos playing, computer games carried out, by using extensively the computers to perform, the demands for those users about the display ports of the computers has also become increasingly diverse. General display cards or built-in display circuits of the computers only provide limited external display ports of fixed specifications for applications. For example, the external display ports of those general laptops usually include only one HDMI connector and a VGA connector; and the existing high-end display cards are also only equipped with two external display ports with the combinations of fixed specifications (two HDMI or one DVI plus one DVI).
The aforementioned limitations of the quantity primarily come from the Basic Input/Output System of the graphics display chip (GPU BIOS). GPU BIOS limits the quantity and specifications of the I/O. Under these limitations, the manufacturers cannot arbitrarily increase the number of the external display ports, and cannot arbitrarily change the specifications of the external display ports, either. They can only change the specifications by rewriting the GPU BIOS program code, but the quantity of ports is still limited (the quantity is simultaneously limited by the number of the pins of the I/O of the GPU).